operation of the Airbus A310 became more frequent as the fleet continued to grow. Concurrently, the number of incidents had also increased in number. Comparing on the number of incidents between Airbus A310 that had been operated by Aeroflot and the Airbus A310 that had been operated by S7 Airlines, the analysis revealed that there had been an increase by two-fold in terms of flight hours per incidents. The level of safety of the Airbus A310 that were operated by S7 Airlines had fallen approximately 4 times lower than that of Aeroflot. Simultaneously, with the rapid expansion of S7 Airlines, the number of requested spare parts for the maintenance of their fleets quickly skyrocketed. While the number of requested spare parts were in the thousands, the available stocks were only in the hundreds. Combined with the difficult customs clearance for importing spare parts from abroad, S7 Airlines eventually had to resort to the deferred defects practices, where damaged part of an aircraft was swapped with the functioning part to rectify it. The aircraft that was involved in the accident, F-OGYP, had also been recently involved in such procedure. On 6 July 2006, three days before the crash, the aircraft flew with a malfunctioning right engine reverser and upon landing the reverser of the left engine became inoperative. During the aircraft's maintenance on the next day, the right engine was fixed with parts from the left engine. The inoperative left engine reverse was listed under deferred defect and the aircraft returned to service on 8 July with the inoperative left engine reverser. According to investigators, said practices were actually in line with the regulations that had been issued by Russian authorities and the minimum equipment list that had been issued by S7 Airlines. The extensiveness of such practices had never been looked into by officials. Russian aviation authorities enacted lax supervision on S7 Airlines deferred defects practices. Lack of supervision eventually caused defects on S7 Airlines fleet to pile up. Analysis by investigators revealed that during the first six months of 2006, there were a whopping amount of 86 defects on the Airbus A310. Such amount of defects might compromise the safety of future flights. The problems were not constricted to the maintenance culture of S7 Airlines fleet as the pilot training was also highlighted by investigators. The evaluation on Captain Shibanov's pilot training revealed that he had been immediately promoted